Electrically-operated switch.



w, 0. Luna ELEiITfliCfiLLfOPK-IRATED SWITCH.

APPLHY' HDN FILED MAR. 2|. I914.

- Patented Ap r. "1,1919.-

INVENTOR Jbw WITNESSES:

.1 '0 all whom, it may concern WALTER o. LUM, OF ILKINSBURG, PENNSYLVANIA, ASSIGNOR T WESTINGHOUSE ELECTRIO AND MANUFACTURING COMPANY, A CORPORATION OF PENN SYLVANIA.

ELECTRICALLY-OPERATED SWITCH.

Specification of Letters Paten'n Patented A a-.1, 1919.

Application filed March 21,1914. Serial No. 826,246.

Be. it known'that- I, IVALTER O. LUM,

citizen of the United States, and a resident of vVilkinsburg, in the county of Allegheny and State of Pennsylvania, have invented a new and-useful Improvement in Electrically- Operate d Switches, of which the following is a specification.

-1\I v invention relates to electrically oper ated switches, and it has special reference to switches ofthis character which are adapted for use with systems of electric motor control; I

My invention has for one of its objects to provide a switch of the character indicated above that shall besimple Lad durable in construction and have the characteristic of operating only when the energy supplied to its actuating winding falls between predetermined limits.

Another object of my invention is to provide means for adjusting the reluctance of one of a pair of substantially parallel magnetic paths in order to vary the current value at which the switch operates.

A switch constructed in accordance with my invention is particularly adapted for use in connection with systems of electric motor control. It has been previously proposed to employ switches having two paths for the magnet flux, one of which predominates to hold the switch open when the energy supplied to the actuating coil exceeds a predetermined value, and the other of which predominates to close the switch when the current supplied to the coil falls within predetermined limits. In my Patent No. 1,138,677, granted May 11, 1915, I have provided a switch having thecharacteristics above described. The reluctance of that magnetic path that is traversed by the flux which operates to hold the switch in an open position, is varied by means of an adjustable screw which operates to vary the distance between a magnetizable member and an armature member. This arrangement possesses the disadvantage of varying the reluctance of the main magnetic circuit as well as that of the auxiliary magnetic circuit which tends to' retain the switch in its open position.

According to my present invention, I p rovide astationary magnetizable member'v'vith an adjustable portion, the, position of which controls the reluctance of the auxiliary magnetic circuit, By means of this arrangement,

a I am thus enabled to change theconditions in one magneticcircuitwithout affecting the 'conditionsin the other circuit.

My invention will be described in .connec-- tion with the accompanying drawings in which the single figure is a side view, in elevation, of a switch constructed in accordance with my invention.

The switch here shown comprisesa slab-or base 1 ofinsulating material, a stationary magnetizable member 2 secured thereto, a

movable armature 3, a stationary switch contact member 4, a cooperatingmovable contact member 5, and an actuating coil 6;

The stationary laminated core member :2.

which is of substantially U-shapc. isv pro-' vided with a pro ectingportion or lug T and a damper Sof any suitablematerial and construction. The stationary mei'nber 2 is also provided with'an ad ustable laminated portion 10. the POSltLOll of which i's-con trolled by means of an adjusting screw 11 I and a helical compression spring. 12.

- The movable armature 3 is provided with a projecting portion 13 which forms an ohtuse angle with the body of'the armature. The armature has a pivotal support on a pin 14 which is secured to a stationarybracket 15. Then the switch is open. the projecting,

portion 13 of the armature is substantially parallel to an arm 16 of the stationary memher 2 and is in engagement with a thin plate 17 ofnon-nlagnetizable material that is tixcd to the outer face of the lug 17. A

.The damper 8 is secured to-the arm 16 adjacent to the projecting arm 13of the armature andoperates to force theleakagc fiux which traverses the arm 13' to pass through the lug T. This arrangement insures thatthe leakage flux exerts a maximuni 'force tending to hold the switch open.

It may be assumed that the switch is open and that the arm 13 occupies the position indicated by dotted lines. If excessive current be supplied to the coil .(na magnetic circuit is energized. which comprises the stationary member 2 and the body portion of the armature 3. Since the arm 16. is smaller in cross section than the remainder of the stationary member .2. it will be saturated and a portion of the flux will traverse the leakage path which comprises the lug 7 and the arm 13 of the armature 3. The switch will then be held in its open position until the current has decreased to such an amountthat the flux traversing the leakage path is insuflicient to hold the-arm 13 in its dotted line position againstthe force of the main magnetic circuit which tends to close the switch.

The armature 3 will then be rocked into the position shown in the draw ing a-iid the switch will be closed.

separated from the lug 7 by a considerable.

distance.

The current value atwhich the switch is closed may be readily adjusted by means of the screw 11 and the spring 12. It will be noted that, as the movable portion 10 approaches the end of the lug 7, the length of the air gap between the lower end of the movable portion 10 and the arm 13 is decreased. thereby decreasing the reluctance of the leakage path and increasing-the force ith which the arm 13 is heldin its dotted Mae position.

it will be noted that I have provided a maple and convenient means for adjusting tilt} current value at which the switch is operated by adjusting the'force with which the switch is held in its open position. This result; is accomplished without in anyway attecting the reluctance of the main magnetic circuit, as, for example by changing the initial position of the armature 3,

I claim as my invention:

1. A magnet comprising a base, a statioir ary magnetizable member mounted thereon and having a magnetizable arm, an armature pivotally mounted on said base near the outer end of said arm and having a main body portion for coacting with said stationary member to constitute a main magnetic circuit and a projecting portion for coacting with the inner end of said arm to constitute 5 an auxiliary magnetic circuit, said projecting portion extei'iding substantially parallel to said arm when said armature occupies one extreme position and at an angle to said assie-e the outer end of said one arm and having a main body portlon for coactmgr with said stationary membtrto constitute a main magnetic circuit and having a projecting portion for coacting with said projection, said body portions and said other arm to constitute an auxiliary magnetic circuit, said projecting portion extending substantially parallel to said one arm when said armature occupies one extreme position and at an angle to said one arm when said armature occupies its other extreme position, means for magnetically insulating said projecting portion from said one arm except atsaid projection, a magnetizable member adjustably mounted near said projection and separated from said projecting portion, whereby adjustment of said adjustably mounted mem- H her will vary the reluctance of said auxiliary circuit without varying the reluctance of said main circuit, a single coil mounted upon said other arm for energizing said circuits, a stationary contact member, and a movable contact member cooperating therewith carried by said armature.

In testimony whereof I have hereunto subscribed my name this 13th day of March.

VALTER O. HUM. il itnesses 1 W. M. Coonrxsrox, B. B. Hues. 

